The present application claims priority under 35 U.S.C. xc2xa7 119 of German Patent Application No. 198 22 145.2, filed on May 16, 1998, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a deflection compensation (sag adjusting) roll having a roll jacket that is rotatably supported on a crosspiece by roller bearings and a process for rotatably supporting a roll jacket on a crosspiece in a deflection compensation roll.
2. Discussion of Background Information
Rolls such as those generally discussed above are frequently utilized in calenders for processing a material web. In particular, such rolls are utilized in paper calenders.
Generally, ram-like support elements are disposed between the crosspiece (or carrier) and the roll jacket. When pressure is applied to the support elements, they can counteract deflection or sagging of the roll jacket. Because of this, it is accepted that the crosspiece sags somewhat. In an alternative design, it is also possible to fill one half of the interior of the roll jacket with a hydraulic fluid to which pressure is applied. By reducing the pressure in the region of the rams, it is also possible to obtain a selective pressure or force load on the roll. However, the risk exists that the crosspiece will sag somewhat relative to the roll jacket. In both cases, there is a small but no longer negligible inclination of the crosspiece relative to the roll jacket in the region of the roller bearings.
For this reason, a spherical roller bearing is used on at least one end of the roll jacket. Since the outer ring rotates with the roll jacket, there are high frictional forces due to the variable load on the jacket. This results in certain wear and in reduced service life.
The types of bearings available are limited since it is necessary, in a roller bearing, to equip one end with a fixed bearing and the other end with a movable bearing.
The present invention relates to a roller bearing for use in a roll and to other type bearings. The present invention is directed to a deflection compensation (sag adjustment) roll of the type generally discussed above that includes roll bearings composed of radial load-carrying bearings (hereinafter xe2x80x9cradial bearingsxe2x80x9d) and a hydrostatic bearing arrangement that acts in the axial direction.
Thus, in accordance with the exemplary embodiment of the present invention, the radial bearing is uncoupled from the axial bearing. Thus, it is possible to use known types of bearings for the roller bearings which can absorb only radial forces, i.e., not axial forces. The axial forces are completely absorbed by the hydrostatic bearing arrangement. Under these conditions, it is also possible to use roller bearings having convex, oblong-shaped rolling elements between an inside ring and an outside ring. In this manner, the profile radius is substantially larger than that of barrel-shaped roller bearings or spherical roller bearings. Further, the races on the inside ring and the outside ring have an appropriately large race radius. Such bearings are, e.g., available from the company SKF under the name CARB-roll bearings (see, e.g., SKF company publication: The CARB-Roll Bearingxe2x80x94The Better Solution, e.g., in Drying Cylinders on the Guide End). Such bearings permit relatively large angles of inclination and also relatively large axial displacements between the inner ring and the outer ring. However, these bearings are not capable of acting as fixed bearings. The axial support, as mentioned, is provided by the hydrostatic bearing arrangement. Since the hydrostatic bearing arrangement generates relatively low frictional losses and also operates relatively free of wear, in accordance with the present invention, it is possible to match the service life of the radial bearing and the axial bearing to each other.
Preferably, the bearing arrangement has a first axially oriented support surface, which works along with a piston-cylinder arrangement and a second oppositely oriented support surface, which works along with a support shoe arranged in the axial direction relative to the crosspiece. Thus, the two support surfaces are surrounded in tong-like fashion and retained by the piston-cylinder arrangement and the support shoe. Accordingly, the piston-cylinder arrangement may be used to readjust axial movements of the roll jacket to ensure that both support surfaces and their corresponding opposing elements contact each other. Of course, the axial displacement path of the piston-cylinder arrangement must be designed such that it can, if necessary, keep pace with and balance the corresponding differences in length of the roll jacket. However, these may be estimated or calculated in advance with adequate accuracy.
Moreover, the piston-cylinder arrangement may have a ring piston which surrounds the crosspiece. The ring piston may have the advantage that the compressive forces in the circumferential direction are distributed virtually uniformly everywhere, such that no periodic changes, which could result in vibration or some other phenomenon, can occur during a rotation of the roll jacket.
Advantageously, the piston and the support shoe have bearing pockets which are coupled to the same pressure source. Since the bearing pockets act on opposite sides of the roll jacket or other parts connected therewith, on which the support surfaces are located, it may be ensured that an equilibrium of forces always exists between the roll jacket and the crosspiece. This may also be true when the bearing pockets have the same active surface and are provided with the same throttle resistance in their feeder line. If the throttle resistances differ greatly, due to, e.g., different line lengths, it may also be possible to create an appropriate balance through the effective surface of the bearing pockets.
Advantageously, the support surfaces may be located on the roll jacket and the piston-cylinder arrangement, and the support shoe may be located on the crosspiece. This arrangement may simplify the feeding of the hydraulic fluid which has to be supplied only to a stationary part, i.e., the crosspiece.
Preferably, the bearing arrangement may include a disk which is acted upon on both sides. The disk may be coupled with the roll jacket and may be surrounded in a tong-like fashion by the bearing arrangement. Thus, the roller bearing, which is adjacent to the hydrostatic bearing arrangement, is the fixed bearing. The other bearing is the movable bearing.
In an alternative embodiment of the present invention, the bearing arrangement may have a first annular disk positioned on one roll end and a second annular disk positioned on the other roll end. The first annular disk and the second annular disk may be arranged to work with the piston and support shoe, respectively. In this arrangement, there is a tong-like mounting of the roll jacket, in which the jaws of the tongs are roughly as far apart as the effective working width of the roll jacket.
It may be preferable that the piston and the support shoe act on the annular disks axially from the outside. In this embodiment, the axial interior of the roll jacket may remain free for the built-in parts necessary for deflection or sag compensation, e.g., hydrostatic support shoes. When the hydrostatic axial bearing arrangement is divided into the two parts which are positioned adjacent to the roll bearing, the piston in the piston-cylinder arrangement must travel a somewhat longer path, since it must compensate for greater differences in length of the roll jacket. Thus, the radial bearing on which the support shoe is positioned is utilized as the fixed bearing, and the radial bearing on which the piston-cylinder arrangement is positioned is utilized as the movable bearing.
It may be preferable that the annular disks form an axial seal with the support shoe or the piston-cylinder arrangement. Such an axial seal may be necessary when the interior of the roll jacket is to be placed under hydraulic pressure. A seal between the annular disks and the roll jacket can be achieved in a relatively problem free manner. The same is true for a seal between either the support shoe or the piston-cylinder arrangement and the crosspiece. Since the hydrostatic pressure of the bearing pockets is present on the contact surfaces, the seal between the moving surfaces, i.e., between one annular disk and the support shoe and between the piston-cylinder arrangement and the other support disk, can be managed relatively well since. While this arrangement may result in certain leakage of the hydraulic fluid radially outwardly, no pressure escapes from the interior of the roll jacket.
Advantageously, the support shoe and/or the piston-cylinder arrangement may be tiltable relative to the crosspiece. Thus, it may be ensured that despite a certain deflection or sagging of the crosspiece, it is always possible to obtain plane-parallel contact of the support shoe or piston-cylinder arrangement with the annular disks or disk. Such a tiltable mounting may be achieved, e.g., in that the support shoe is supported in an axially oriented spherical cap, or permits the piston to assume somewhat of an angle relative to the cylinder.
The present invention is directed to a deflection adjustment roll that includes a crosspiece, roller bearings composed of radial bearings and at least one hydrostatic bearing arrangement, and a roll jacket, which is rotatably supported on the crosspiece by the roller bearings. The at least one hydrostatic bearing arrangement acts in the axial direction.
In accordance with another feature of the present invention, the hydrostatic bearing arrangement may include a piston-cylinder arrangement, a support shoe, which is fixed in the axial direction relative to the crosspiece, a first axially oriented support surface being adapted for coupling to the piston-cylinder arrangement, and a second axially oriented support surface oppositely oriented with respect to the first axially oriented support surface being adapted for coupling with the support shoe. Moreover, the piston-cylinder arrangement may include a ring piston arranged to surround the crosspiece. Further, a pressure source may be provided, and the piston and the support shoe may have bearing pockets connected to the pressures source. Further still, the first and second support surfaces are coupled to the roll jacket. The piston-cylinder arrangement and the support shoe may be coupled to the crosspiece. Still further, at least one of the support shoe and the piston-cylinder arrangement are tiltably mounted relative to the crosspiece.
According to still another feature of the present invention, the hydrostatic bearing arrangement may include a disk. The disk may be composed of two axial sides adapted to exerted upon with a pressure.
According to a further feature of the present invention, a piston and a support shoe may be provided. The roll jacket includes a first and a second bearing end, the hydrostatic bearing arrangement includes a first annular disk positioned at the first bearing end and a second annular disk positioned at the second bearing end, the piston is positioned to act on the first annular disk, and the support shoe is positioned to act on the second annular disk.
In accordance with a still further feature of the present invention, the piston and support shoe are positioned to act on axially outer surfaces of the first and second annular disks, respectively. Further, the first and second annular disks may be positioned to form an axial seal with a respective one of the piston and the support shoe.
According to yet another feature of the present invention, the at least one hydrostatic bearing arrangement includes a plurality of hydrostatic bearing arrangements. The plurality of hydrostatic bearing arrangements may be positioned axially inside of the radial roll bearings. Still further, the at least one hydrostatic bearing arrangement includes a plurality of hydrostatic bearing arrangements, one of the plurality of hydrostatic bearing arrangements includes a first and second bearing element, and the first and second bearing elements are slidably coupled along a plane oblique to axial direction. Further still, the at least one hydrostatic bearing arrangement includes a plurality of hydrostatic bearing arrangements, and the plurality of hydrostatic bearing arrangements are coupled to the crosspiece. Further, a bearing ring is postionable over the crosspiece, the at least one hydrostatic bearing arrangement includes a plurality of hydrostatic bearing arrangements, and the plurality of hydrostatic bearing arrangements are coupled to the bearing ring.
According to another feature of the present invention, the at least one hydrostatic bearing arrangement is positioned axially between the radial roller bearings. According to still another feature of the present invention, the at least one hydrostatic bearing arrangement is coupled to the crosspiece. In accordance with still another feature of the present invention, a bearing ring may be postionable over the crosspiece, and the at least one hydrostatic bearing arrangement may be coupled to the bearing ring.
According to yet another feature of the present invention, the present invention is directed to a process for treating a web in an apparatus that includes the deflection compensation roll. The process includes forming a nip between the deflection compensation roll and a counter roll, and guiding the web through the nip. Further, the process may include loading the deflection compensation roll by pressing the roll jacket in a direction away from the crosspiece. Moreover, the process may include absorbing axial forces on the roll jacket with the at least one hydrostatic bearing arrangement.
The present invention is directed to a process for rotatably supporting a roll jacket on a crosspiece that extends through the roll jacket in a deflection compensation roll. The process includes positioning radial roller bearings at each bearing end of the deflection compensation roll and between the crosspiece and the roll jacket, wherein the radial roll bearings absorb radial forces, and positioning at least one hydrostatic bearing arrangement between the crosspiece and the roll jacket, wherein the at least one hydrostatic bearing arrangement absorbs axial forces.
In accordance with another feature of the present invention, the at least one hydrostatic bearing arrangement includes a piston-cylinder arrangement, a support shoe that is fixed in the axial direction relative to the crosspiece, a first axially oriented support surface, and a second axially oriented support surface oppositely oriented with respect to the first axially oriented support surface. The process further includes biasing the piston of the piston-cylinder arrangement toward the first axially oriented support surface, and positioning the support shoe opposite the second axially oriented support surface. Moreover, the process further includes coupling the first and second support surfaces to the roll jacket, and coupling the piston-cylinder arrangement and the support shoe to the crosspiece.
According to still another feature of the present invention, the deflection compensation roll may include a piston, a support shoe, the hydrostatic bearing arrangement including a first annular disk positioned at a first bearing end of the deflection compensation roll and a second annular disk positioned at a second bearing end of the deflection compensation roll. The process may further include positioning the piston to act on the first annular disk, and positioning the support shoe to act on the second annular disk. Further, the process may include positioning the piston and support shoe to act on axially outer surfaces of the first and second annular disks, respectively. Still further, the process may include positioning the first and second annular disks to form an axial seal with a respective one of the piston and the support shoe.
According to a still further feature of the present invention, the at least one hydrostatic bearing arrangement may include a plurality of hydrostatic bearing arrangements, and the process may further include positioning the plurality of hydrostatic bearing arrangements axially inside of the radial roller bearings.
In accordance with another feature of the present invention, the at least one hydrostatic bearing arrangement may include a plurality of hydrostatic bearing arrangements, the process may further include coupling the plurality of hydrostatic bearing arrangements to the crosspiece.
In accordance with still another feature of the present invention, the deflection compensation roll includes a bearing ring postionable over the crosspiece and the at least one hydrostatic bearing arrangement comprising a plurality of hydrostatic bearing arrangements, and the process may further include coupling the plurality of hydrostatic bearing arrangements to the bearing ring.
According to a further feature of the present invention, the process may further include positioning the at least one hydrostatic bearing arrangement axially between the radial roll bearings. According to still another feature of the present invention, the process may further include coupling the at least one hydrostatic bearing arrangement to the crosspiece.
In accordance with yet another feature of the present invention, the deflection compensation roll may include a bearing ring postionable over the crosspiece, and the process may further include coupling the at least one hydrostatic bearing arrangement to the bearing ring.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.